Means for improving burnout of consumable cartridge cases

ABSTRACT

A weapons system for promoting the complete combustion of a consumable cartridge case used therewith. The system includes means for uniformly radially spacing the cartridge case from the breech or chamber wall of the gun chamber which permits the circulation of hot gases therebetween.

Unlted States Patent [15] 3,696,748 Picard et al. Oct. 10,1972

[54] MEANS FOR IMPROVING BURNOUT 21,253 8/1958 Gomez et a1 ..102/DIG. 1 OF CONSUMABLE CARTRIDGE CASES 707,401 8/ 1902 Dorr 102/97 X 72 I t P Pi M t MUSSCI' I 1 {,fig gf 2,353,934 7/1944 Schreib ..102/97 pellrwest Orange FOREIGN PATENTS 0R APPLICATIONS [73] Assignee: The United States of America as 3 004 1907 Gr eat Britain ..42/76 gi by the secretary 1,208 1862 Great Britain ..42/73 y 412,012 6/1934 Great Britain ..102/43 [22] Filed: Dec. 29, 1969 605,136 7/1948 Great Britain ..42/76 l No: Great Britain Related U.S. Application Data Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Stephen C. Bentley [63] g ggg gsgg of Attorney-Harry M. Saragovitz, Edward J. Kelly, Herbert Bet] and S. Dubrofi' [52] U.S. Cl ..102/38, 42/76, l02/DIG. 1,

102/43 p [57] ABSTRACT [51] Int. Cl. ..F42b 5/18, F42b 5/30 A Weapons system for promoting the complete [58] Field of Search ..42/76, 78; 89/ l4, l5; bustion of a consumable cartridge case used 102mm 43 43 97 therewith. The system includes means for uniformly radially spacing the cartridge case from the breech or [56] References and chamber wall of the gun chamber which permits the UNITED STATES PATENTS circulation of hot gases therebetween. a

15,369 7/1856 Buckel et al ..102/D1G. l 1 Claim, 6 Drawing Figures r &\\'\\\ Zlr PATENTED "RT 1U 3 696. 74.8

lNVENTORfi JEAN P. PICAZD W\LL.\AM O. 5EAL$ LAWRENCE W. PELL 5.3 M ATTORNEYS.

MEANS FOR IMPROVING BURNOUT OF CONSUMABLE CARTRIDGE CASES This application is a continuation-in-part of our copending application Ser. No. 659,562, filed Aug. 2, 1967, for Means for Improving Burnout of Consumable Cartridge Cases, now abandoned.

The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to a weapons system and more particularly to consumable cartridge cases for use in such system, the cases achieving complete burnout and thus leaving no residue inside the chamber of the gun after being fired therethrough.

The advent of consumable cartridge cases emphasized the problem of residue remaining in the chamber of a gun after firing. The buildup of residue from firings can cause misfiring of a subsequent round and/or destruction of the gun through destruction of the gun chamber, and the like.

In the past, experts in the field of interior ballistics have tried different methods in attempting to solve this problem. These methods included, among others: Providing a highly porous case of a low density foam, or incorporating explosive oxidizers into the case wall. None of these methods proved highly successful. For example, the use of a highly porous case presented the additional problem of unwanted moisture penetration into the cartridge case which not only hindered ignition of the propellant charge, but of the igniter as well. A protective coating was then applied to the outer case surface to prevent moisture penetration, but this coating hindered complete burnout. The use of low density foams would readily burn out but the physical strength of the cartridge cases at low densities was poor. It must be borne in mind that strength is directly related to the density and therefore it is essential that the highest den sity possible be used. The use of explosive oxidizers incorporated into cartridge cases presented a hazard to safe handling, and the addition of the oxidizers impaired the physical strength of the case.

The present invention substantially eliminates the aforementioned problems by providing novel spacing means between the chamber wall and the cartridge case, which means does not impair the strength of the case and, will increase the burnout capabilities of the case without concomitant residue.

It is therefore an object of the present invention to provide a weapons system which substantially assures complete burnout of consumable cartridge cases used therewith.

Another object of the invention is to provide protrusions or channels on a wall of a cartridge case or gun chamber which effectively promotes substantially complete burnout of consumable cartridge cases used with the weapons system.

The above objects as well as others together with the benefits and advantages of the invention will be apparent upon reference to the detailed description set forth below, particularly when taken in conjunction with the drawings annexed hereto in which:

FIG. 1 illustrates an axial section of one embodiment of our invention, the shell depicted being a 37 mm.

FIG. 2 is a section of FIG. 1 taken along line 22 thereof with the priming means and propellant not shown.

FIGS. 3-6 are transverse sections of modifications of the embodiment shown in FIG. 1, the channels and protrusions extending the entire length of the gun chamber wall or cartridge case, similarly to the scrim 18 designated in FIG. 1.

Referring now to the drawings, and more particularly to FIGS. 1 and 2 thereof, a consumable cartridge case 10 having an outer wall 12 is separated from inner gun chamber wall 14 of a breech or gun chamber 16 by a spacer 18 in the form of a mesh or scrim of natural or synthetic fibers. Scrim 18 is placed around the outside of the case in one or more layers and may be wrapped loosely, cemented or otherwise attached to the cartridge case wall 12. The scrim may be a plastic or synthetic fiber such as polyethylene terephthalate, sold under the trademark Dacron, a product of duPont. A 20 denier mesh Dacron fiber has been found to perform satisfactorily, although other size fibers and other synthetic fibers may be used advantageously with our invention, e.g., fibrous spacers of cellulosic origin.

The consumable cartridge case also includes propellant 20, a projectile 22, primer 24, and a rotation band 26. The standard barrel 28 and firing means 29 are also provided in the weapons system.

In accordance with usual practice, the consumable cartridge case will be placed within a gun chamber where negligible air space exists between the case and chamber wall. Upon firing of the cartridge, the case wall expands and seats against the breech wall or inner gun chamber wall thus acting as a heat sink. In the modification of our invention just described, the scrim l8 effectively promotes complete burnout of the cartridge case by allowing the hot combustion gases to pass rearwardly between the meshes of the scrim, thus aiding in the burning of the cartridge case from the outside. The interior portions of the cartridge case are effectively burned by the propellant itself. It can readily be seen therefore that our scrim substantially eliminates any transfer of heat to the breech of chamber wall while yet promoting complete burnout of the consumable cartridge case.

As seen in FIG. 3, a consumable cartridge case 30 has portions of its outer surface separated from the inner chamber wall 32 of the breech 34. Channels 36 are engraved along the entire length of the gun chamber wall, thus effectively providing a spacing means between the cartridge case and chamber wall for permitting hot combustion gases to pass therethrough to promote complete burnout of the case. The modifications of FIGS. 3-6 are transverse sectional views only, it being understood that the channels and protrusions extend for the entire length of the inner chamber wall or cartridge case.

FIG. 4 illustrates the use of engraved protrusions 48 on the inner chamber wall 42 of breech block 44. Spaces 46 constitute a portion of the gun chamber. The cartridge case is shown at 40.

As seen in FIG. 5, a consumable cartridge case 50 has channels 52 molded into the outer wall 54 thereof. The case 50 fits snugly against the inner chamber wall 56. Numeral 58 represents the outer wall of the breech block. Gases pass through channels 52.

FIG. 6 illustrates the use of molded protrusions on the outer wall 66 of the consumable cartridge 60. The outer wall of the breech is designated at 62.

In the 37mm shell depicted, we have found that one layer of 20 mesh Dacron scrim was necessary to achieve complete burnout. However, in a 105 mm gun where the firing pressure is increased from 37,000 PS1 to approximately 60,000 psi, two or three additional wraps of scrim are necessary to obtain complete burnout.

We wish it to be understood that we do not desire to be limited to the exact details described, for obvious modifications will occur to a person skilled in the art.

We claim:

1. In a consumable cartridge case for use in a gun chamber and having a projectile, propellant, and a 

1. In a consumable cartridge case for use in a gun chamber and having a projectile, propellant, and a primer, said case having outer wall portions of low density foam material surrounding said propellant, means for promoting substantially complete combustion of said cartridge case upon firing of the cartridge, said means having the capability of radially uniformly spacing at least outer portions of said cartridge case from the wall of said gun chamber for the entire length and circumference of said cartridge case, said means including at least one layer of polyethylene terephthalate mesh attached to and substantially surrounding the outer wall of said case. 